fix(desktop): don't false-timeout long prompt.submit turns (MoA, deep reasoning) (#56411)

prompt.submit is fire-and-forget — turn completion is signaled by stream /
message.complete events, not the RPC return — but it inherited the generic 30s
default RPC timeout. A turn that legitimately takes >30s to ACK (MoA presets
running references + aggregator in series, deep reasoning, large tool chains)
popped a false 'request timed out: prompt.submit' toast at 30s while the turn
was still running and streamed its real answer in 60-120s later (#55024).

Add PROMPT_SUBMIT_REQUEST_TIMEOUT_MS (1_800_000 = the backend's
agent.gateway_timeout ceiling) and pass it on all four prompt.submit call sites
(submit, resume-recovery retry, regenerate, rewind), mirroring the existing
SESSION_LIST_REQUEST_TIMEOUT_MS opt-out precedent. Widen the GatewayRequest
type (+ the inline requestGateway prop type) to carry the optional timeoutMs the
runtime impl already accepts.

Tests: use-prompt-actions/index.test.tsx 34/34 pass; tsc -b clean.

apps/desktop/src/app/session/hooks/use-prompt-actions/index.test.tsx

@@ -12,6 +12,7 @@ import { uploadComposerAttachment, usePromptActions } from '.'
 
 vi.mock('@/hermes', () => ({
   getProfiles: vi.fn(async () => ({ profiles: [] })),
+  PROMPT_SUBMIT_REQUEST_TIMEOUT_MS: 1_800_000,
   setApiRequestProfile: vi.fn(),
   transcribeAudio: vi.fn()
 }))
@@ -365,10 +366,14 @@ describe('usePromptActions submit / queue drain semantics', () => {
     // every delta of this brand-new turn.
     expect(seeds.length).toBeGreaterThan(0)
     expect(seeds.every(s => s.interrupted === false)).toBe(true)
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'hello after a stop'
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'hello after a stop'
+      },
+      1_800_000
+    )
   })
 
   it('a fromQueue drain sends even when busyRef is still true on the settle edge', async () => {
@@ -390,10 +395,14 @@ describe('usePromptActions submit / queue drain semantics', () => {
     const accepted = await handle!.submitText('queued message', { fromQueue: true })
 
     expect(accepted).toBe(true)
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'queued message'
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'queued message'
+      },
+      1_800_000
+    )
   })
 
   it('a rejected fromQueue drain returns false (entry stays queued) and a later retry sends it', async () => {
@@ -430,10 +439,14 @@ describe('usePromptActions submit / queue drain semantics', () => {
 
     const second = await handle!.submitText('please send me', { fromQueue: true })
     expect(second).toBe(true)
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'please send me'
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'please send me'
+      },
+      1_800_000
+    )
   })
 
   it('rides out a transient "session busy" so the user never sees it (retries, no error bubble)', async () => {
@@ -593,11 +606,15 @@ describe('usePromptActions restoreToMessage', () => {
 
     // Ordinal 0 = "truncate before the first visible user message": the gateway
     // drops that turn and everything after, then runs the same text again.
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'first prompt',
-      truncate_before_user_ordinal: 0
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'first prompt',
+        truncate_before_user_ordinal: 0
+      },
+      1_800_000
+    )
     expect((lastState.messages as { id: string }[]).map(m => m.id)).toEqual(['u1'])
     expect(lastState.busy).toBe(true)
   })
@@ -656,11 +673,15 @@ describe('usePromptActions restoreToMessage', () => {
 
     expect(requestGateway).toHaveBeenCalledWith('session.interrupt', { session_id: RUNTIME_SESSION_ID })
     expect(submitAttempts).toBe(2)
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'first prompt',
-      truncate_before_user_ordinal: 0
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'first prompt',
+        truncate_before_user_ordinal: 0
+      },
+      1_800_000
+    )
   })
 
   it('rejects non-user targets and unknown ids without touching the gateway', async () => {
@@ -697,11 +718,15 @@ describe('usePromptActions restoreToMessage', () => {
       userOrdinal: 0
     })
 
-    expect(requestGateway).toHaveBeenCalledWith('prompt.submit', {
-      session_id: RUNTIME_SESSION_ID,
-      text: 'first prompt',
-      truncate_before_user_ordinal: 0
-    })
+    expect(requestGateway).toHaveBeenCalledWith(
+      'prompt.submit',
+      {
+        session_id: RUNTIME_SESSION_ID,
+        text: 'first prompt',
+        truncate_before_user_ordinal: 0
+      },
+      1_800_000
+    )
     expect((lastState.messages as { id: string }[]).map(m => m.id)).toEqual(['u1'])
   })
 })

apps/desktop/src/app/session/hooks/use-prompt-actions/index.ts

@@ -2,7 +2,7 @@ import type { AppendMessage, ThreadMessage } from '@assistant-ui/react'
 import { useStore } from '@nanostores/react'
 import { type MutableRefObject, useCallback, useEffect, useRef } from 'react'
 
-import { transcribeAudio } from '@/hermes'
+import { transcribeAudio, PROMPT_SUBMIT_REQUEST_TIMEOUT_MS } from '@/hermes'
 import { useI18n } from '@/i18n'
 import { stripAnsi } from '@/lib/ansi'
 import { branchGroupForUser, type ChatMessage, chatMessageText, textPart } from '@/lib/chat-messages'
@@ -159,7 +159,7 @@ interface PromptActionsOptions {
   createBackendSessionForSend: (preview?: string | null) => Promise<string | null>
   handleSkinCommand: (arg: string) => string
   refreshSessions: () => Promise<void>
-  requestGateway: <T>(method: string, params?: Record<string, unknown>) => Promise<T>
+  requestGateway: <T>(method: string, params?: Record<string, unknown>, timeoutMs?: number) => Promise<T>
   resumeStoredSession: (storedSessionId: string) => Promise<void> | void
   selectedStoredSessionIdRef: MutableRefObject<string | null>
   startFreshSessionDraft: () => void
@@ -665,11 +665,15 @@ export function usePromptActions({
       })
 
       try {
-        await requestGateway('prompt.submit', {
-          session_id: activeSessionId,
-          text: userText,
-          truncate_before_user_ordinal: truncateBeforeUserOrdinal
-        })
+        await requestGateway(
+          'prompt.submit',
+          {
+            session_id: activeSessionId,
+            text: userText,
+            truncate_before_user_ordinal: truncateBeforeUserOrdinal
+          },
+          PROMPT_SUBMIT_REQUEST_TIMEOUT_MS
+        )
       } catch (err) {
         updateSessionState(activeSessionId, state => ({
           ...state,
@@ -702,11 +706,15 @@ export function usePromptActions({
       }
 
       const submit = () =>
-        requestGateway('prompt.submit', {
-          session_id: sessionId,
-          text,
-          ...(truncateOrdinal !== undefined && { truncate_before_user_ordinal: truncateOrdinal })
-        })
+        requestGateway(
+          'prompt.submit',
+          {
+            session_id: sessionId,
+            text,
+            ...(truncateOrdinal !== undefined && { truncate_before_user_ordinal: truncateOrdinal })
+          },
+          PROMPT_SUBMIT_REQUEST_TIMEOUT_MS
+        )
 
       if (interruptFirst) {
         await interrupt()

apps/desktop/src/app/session/hooks/use-prompt-actions/submit.ts

@@ -1,6 +1,7 @@
 import { type MutableRefObject, useCallback } from 'react'
 
 import type { Translations } from '@/i18n'
+import { PROMPT_SUBMIT_REQUEST_TIMEOUT_MS } from '@/hermes'
 import { type ChatMessage, textPart } from '@/lib/chat-messages'
 import { optimisticAttachmentRef } from '@/lib/chat-runtime'
 import { setMutableRef } from '@/lib/mutable-ref'
@@ -252,7 +253,9 @@ export function useSubmitPrompt(deps: SubmitPromptDeps) {
         let submitErr: unknown = null
 
         try {
-          await withSessionBusyRetry(() => requestGateway('prompt.submit', { session_id: sessionId, text }))
+          await withSessionBusyRetry(() =>
+            requestGateway('prompt.submit', { session_id: sessionId, text }, PROMPT_SUBMIT_REQUEST_TIMEOUT_MS)
+          )
         } catch (firstErr) {
           if (isSessionNotFoundError(firstErr) && selectedStoredSessionIdRef.current) {
             // Re-register the session in the gateway and get a fresh live ID.
@@ -264,7 +267,9 @@ export function useSubmitPrompt(deps: SubmitPromptDeps) {
 
             if (recoveredId) {
               activeSessionIdRef.current = recoveredId
-              await withSessionBusyRetry(() => requestGateway('prompt.submit', { session_id: recoveredId, text }))
+              await withSessionBusyRetry(() =>
+                requestGateway('prompt.submit', { session_id: recoveredId, text }, PROMPT_SUBMIT_REQUEST_TIMEOUT_MS)
+              )
             } else {
               submitErr = firstErr
             }

apps/desktop/src/app/session/hooks/use-prompt-actions/utils.ts

@@ -6,7 +6,11 @@ import { type CommandsCatalogLike, filterDesktopCommandsCatalog } from '@/lib/de
 import { isProviderSetupErrorMessage } from '@/lib/provider-setup-errors'
 import type { ComposerAttachment } from '@/store/composer'
 
-export type GatewayRequest = <T>(method: string, params?: Record<string, unknown>) => Promise<T>
+export type GatewayRequest = <T>(
+  method: string,
+  params?: Record<string, unknown>,
+  timeoutMs?: number
+) => Promise<T>
 
 export function delay(ms: number): Promise<void> {
   return new Promise(resolve => setTimeout(resolve, ms))

apps/desktop/src/hermes.ts

@@ -49,6 +49,15 @@ import type {
 
 const DEFAULT_GATEWAY_REQUEST_TIMEOUT_MS = 30_000
 const SESSION_LIST_REQUEST_TIMEOUT_MS = 60_000
+// prompt.submit is effectively fire-and-forget: turn completion is signaled by
+// stream / message.complete events, NOT by the RPC return. A long turn (MoA
+// presets running references + aggregator in series, deep reasoning, large tool
+// chains) can legitimately take minutes to ACK, so bounding the ack by the
+// generic 30s default surfaces a false "request timed out" toast while the turn
+// is still running and will succeed (issue #55024). Match the backend's
+// agent-turn ceiling (agent.gateway_timeout = 1800s) so the ack timeout only
+// ever fires when the turn itself would have been abandoned server-side.
+export const PROMPT_SUBMIT_REQUEST_TIMEOUT_MS = 1_800_000
 
 export type {
   ActionResponse,